Semiconductor device having reduced capacitance between source and drain pads

ABSTRACT

A semiconductor device includes an active layer having an active region, a source electrode, a drain electrode, a gate electrode, a source metal layer, a drain metal layer, and a source pad. The source metal layer and the drain metal layer are electrically connected to the source electrode and the drain electrode, respectively. An orthogonal projection of the drain metal layer on the active layer each forms a drain metal layer region. The source pad is electrically connected to the source metal layer. An orthogonal projection of the source pad on the active layer forms a source pad region overlapping the drain metal layer. An area of an overlapping region between the source pad region and the drain metal layer region is smaller than or equal to 40% of an area of the drain metal layer region.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part application of U.S.application Ser. No. 15/678,102, filed Aug. 15, 2017, which is acontinuation-in-part application of U.S. application Ser. No.15/297,123, filed Oct. 18, 2016, now U.S. Pat. No. 10,084,076, issued onSep. 25, 2018, which is a continuation application of U.S. applicationSer. No. 14/496,471, filed Sep. 25, 2014, now U.S. Pat. No. 9,508,843,issued on Nov. 29, 2016, which claims priority to Taiwan ApplicationSerial Number 103106659, filed Feb. 27, 2014 and Taiwan ApplicationSerial Number 103114340, filed Apr. 21, 2014, which are hereinincorporated by reference in their entireties. U.S. application Ser. No.14/496,471 is a continuation-in-part application of U.S. applicationSer. No. 14/185,322, filed Feb. 20, 2014, now U.S. Pat. No. 8,957,493,issued on Feb. 17, 2015, which claims priority to Taiwan ApplicationSerial Number 102132512, filed Sep. 10, 2013, which are hereinincorporated by reference in their entireties.

BACKGROUND Field of Disclosure

The present disclosure relates to a semiconductor device.

Description of Related Art

In order to shrink the area of a semiconductor device, the drain pad orthe source pad of the semiconductor device may be fabricated to beoverlapped with the source electrodes or the drain electrodes. However,the overlapping between source and drain may cause high stress which maydamage the semiconductor device. Furthermore, if the length of the padis too long, the resistance may increase, and the current uniformity maybecome worse. Thus, there is a need to provide a semiconductor devicethat may reduce the resistance and improve the uniformity of thecurrent.

SUMMARY

A semiconductor device includes an active layer, a source electrode, adrain electrode, a gate electrode, a source metal layer, a drain metallayer, and a source pad. The active layer has an active region. Thesource electrode, the drain electrode, and the gate electrode aredisposed on the active region of the active layer and extend along afirst direction. The source metal layer is disposed on the active regionand is electrically connected to the source electrode. The drain metallayer is disposed on the active region and electrically connected to thedrain electrode, and an orthogonal projection of the drain metal layeron the active layer forms a drain metal layer region. The source pad isdisposed on the active region, and the source pad is electricallyconnected to the source metal layer. An orthogonal projection of thesource pad on the active layer forms a source pad region that overlapsthe drain metal layer region, and an area of an overlapping regionbetween the source pad region and the drain metal layer region issmaller than or equal to 40% of an area of the drain metal layer region.

In some embodiments, an orthogonal projection of the source metal layeron the active layer forms a source metal layer region. The semiconductordevice further includes a drain pad disposed on the active region, andthe drain pad is electrically connected to the drain metal layer. Anorthogonal projection of the drain pad on the active layer forms a drainpad region that overlaps the source metal layer region, and an area ofan overlapping region between the drain pad region and the source metallayer region is smaller than or equal to 40% of an area of the sourcemetal layer region.

In some embodiments, the source electrode includes a bottom electrodeportion and a top electrode portion. The electrode portion of the sourceelectrode is disposed between the metal layer portion of the sourceelectrode and the active layer.

In some embodiments, the drain electrode includes a bottom electrodeportion and a top electrode portion. The electrode portion of the drainelectrode is disposed between the metal layer portion of the drainelectrode and the active layer.

In some embodiments, the source metal layer further includes a secondbranch portion extending along the first direction.

In some embodiments, the source pad further includes a body portion anda first branch portion. The body portion extends along the firstdirection and the first branch portion extends along the seconddirection.

In some embodiments, the source metal layer includes a first branchportion extending along a second direction different from the firstdirection and a second branch portion extending along the firstdirection.

In some embodiments, the source pad further includes a second branchportion extending along the first direction and electrically connectedto the second branch portion of the source metal layer.

In some embodiments, the drain metal layer further includes a secondbranch portion extending along the first direction.

In some embodiments, the drain pad further includes a body portionextending along the first direction and a first branch portionsextending along the second direction.

In some embodiments, the drain metal layer includes a first branchportion extending along the second direction and a second branch portionextending along the first direction.

In some embodiments, the drain pad further includes a second branchportion extending along the first direction and electrically connectedto the second branch portion of the drain metal layer.

A semiconductor device includes an active layer, a plurality of sourceelectrodes, a plurality of drain electrodes, a plurality of gateelectrodes, a source metal layer, a drain metal layer, and a source pad.The active layer has a plurality of active regions spaced apart fromeach other. The source electrodes, the drain electrodes, and the gateelectrodes are respectively disposed on the active regions of the activelayer, and the gate electrodes are electrically connected with eachother. The source metal layer is electrically connected to the sourceelectrodes. The drain metal layer is electrically connected to the drainelectrodes, and a projection of the drain metal layer on the activelayer forms a drain metal layer region. The source pad is disposed onthe active region, and the source pad is electrically connected to thesource metal layer. An orthogonal projection of the source pad on theactive layer forms a source pad region that overlaps the drain metallayer region, and an area of an overlapping region between the sourcepad region and the drain metal layer region is smaller than or equal to40% of an area of the drain metal layer region.

In some embodiments, a projection of the source metal layer on theactive layer forms a source metal layer region. The semiconductor devicefurther includes a drain pad disposed on the active region, and thedrain pad is electrically connected to the drain metal layer. Anorthogonal projection of the drain pad on the active layer forms a drainpad region that overlaps the source metal layer region, and an area ofan overlapping region between the drain pad region and the source metallayer region is smaller than or equal to 40% of an area of the sourcemetal layer region.

In some embodiments, the semiconductor device further includes a gatebus electrically connected to the gate electrodes.

In some embodiments, the gate bus extends from the gate electrodes andis laterally arranged in a layer stacked between the active layer andthe source metal layer or the drain metal layer.

In some embodiments, the gate electrodes are disposed between the gatebus and the active layer.

A semiconductor device includes an active layer, a first sourceelectrode, a first drain electrode, a first gate electrode, a secondsource electrode, a second drain electrode, a second gate electrode, afirst source metal layer, a first drain metal layer, a second drainmetal layer, and a source pad. The active layer has a first activeregion and a second active region spaced apart from each other. Thefirst source electrode, the first drain electrode, and the first gateelectrode are disposed on the first active region of the active layer.The second source electrode, the second drain electrode, and the secondgate electrode are disposed on the second active region of the activelayer. The first source metal layer is electrically connected to thefirst source electrode. The first drain metal layer is electricallyconnected to the first drain electrode. The second drain metal layer iselectrically connected to the second drain electrode and the firstsource metal layer, and a projection of the second drain metal layer onthe second active layer forms a drain metal layer region. The source padis disposed on the active region, and the source pad is electricallyconnected to the first source metal layer. An orthogonal projection ofthe source pad on the active layer forms a source pad region thatoverlaps the drain metal layer region, and an area of an overlappingregion between the source pad region and the drain metal layer region issmaller than or equal to 40% of an area of the drain metal layer region.

In some embodiments, a projection of the first source metal layer on thefirst active layer forms a source metal layer region. The semiconductordevice further includes a drain pad disposed on the active region, andthe drain pad is electrically connected to the second drain metal layer.An orthogonal projection of the drain pad on the active layer forms adrain pad region that overlaps the source metal layer region, and anarea of an overlapping region between the drain pad region and thesource metal layer region is smaller than or equal to 40% of an area ofthe source metal layer region.

In some embodiments, the semiconductor device includes a second sourcemetal layer electrically connected to the second source electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a semiconductor device according to someembodiments of the present disclosure;

FIG. 2A is a cross-sectional view along line 2A-2A of FIG. 1;

FIG. 2B is a cross-sectional view along line 2B-2B of FIG. 1;

FIG. 3 is a top view of the source electrodes, the drain electrodes, thegate electrodes, and the active layer of the semiconductor device ofFIG. 1;

FIG. 4 is a top view of another semiconductor device according to someembodiments of the present disclosure;

FIG. 5A is a cross-sectional view along line 5A-5A of FIG. 4;

FIG. 5B is a cross-sectional view along line 5B-5B of FIG. 4;

FIG. 6 is a top view of another semiconductor device according to someembodiments of the present disclosure;

FIG. 7A is a cross-sectional view along line 7A-7A of FIG. 6;

FIG. 7B is a cross-sectional view along line 7B-7B of FIG. 6;

FIG. 8 is a top view of another semiconductor device according to someembodiments of the present disclosure;

FIG. 9A is a cross-sectional view along line 9A-9A of FIG. 8;

FIG. 9B is a cross-sectional view along line 9B-9B of FIG. 8;

FIG. 10 is a top view of another semiconductor device according to someembodiments of the present disclosure;

FIG. 11A is a cross-sectional view along line 11A-11A of FIG. 10;

FIG. 11B is a cross-sectional view along line 11B-11B of FIG. 10;

FIG. 12 is a top view of another semiconductor device according to someembodiments of the present disclosure;

FIG. 13 is a top view of another semiconductor device according to someembodiments of the present disclosure;

FIG. 14 is a top view of another semiconductor device according to someembodiments of the present disclosure; and

FIG. 15 is a circuit diagram of the semiconductor device in FIG. 14.

DETAILED DESCRIPTION

Reference will now be made in detail to the present embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or like parts.

FIG. 1 is a top view of a semiconductor device 100 according to someembodiments of the present disclosure, FIG. 2A is a cross-sectional viewalong line 2A-2A of FIG. 1, and FIG. 2B is a cross-sectional view alongline 2B-2B of FIG. 1. Reference is made to FIGS. 1, 2A, and 2B. Thesemiconductor device 100 includes an active layer 110, source electrodes120, drain electrodes 130, gate electrodes 140, source metal layers 150,drain metal layers 160, a source pad 170, and a drain pad 180. Theactive layer 110 has an active region 112. The source electrodes 120,the drain electrodes 130, the gate electrodes 140, the source metallayers 150, and the drain metal layers 160 are disposed on the activeregion 112 of the active layer 110.

The source metal layers 150 and the drain metal layers 160 arealternately arranged along a first direction D1 and extend along thesecond direction D2 different from the first direction D1. For example,the first direction D1 is substantially perpendicular to the seconddirection D2 as shown in FIG. 1. The source metal layers 150 are spacedfrom each other, and the drain metal layers 160 are spaced from eachother. The term “substantially” as used herein may be applied to modifyany quantitative representation which could permissibly vary withoutresulting in a change in the basic function to which it is related.

The source pad 170 ad the drain pad 180 extend along the first directionD1. That is, the source pad 170 and the drain pad 180 are substantiallyparallel to each other. As illustrated in FIGS. 1 and 2B, the source pad170 is electrically connected to the source metal layers 150 and thesource electrodes 120. The source pad 170 is at least partially disposedon the active region 112 of the active layer 110. For example, aprojection of the source pad 170 on the active layer 110 is within theactive region 112 or overlaps the active region 112. That is, the sourcepad 170 overlaps at least a portion of the source electrodes 120, and atleast a portion of the gate electrodes 140, and optionally overlaps atleast a portion of the drain electrodes 130. As illustrated in FIGS. 1and 2A, the drain pad 180 is electrically connected to the drain metallayer 160 and the drain electrodes 130. The drain pad 180 is at leastpartially disposed on the active region 112 of the active layer 110. Forexample, a projection of the drain pad 180 on the active layer 110 iswithin the active region 112 or overlaps the active region 112. That is,the drain pad 180 overlaps at least a portion of the drain electrodes130, at least a portion of the gate electrodes 140, and/or at least aportion of the source electrodes 120.

The semiconductor device 100 further includes a dielectric layer 280.For clarity, the dielectric layer 280 is illustrated in FIGS. 2A and 2B.The dielectric layer 280 covers the source metal layers 150 and thedrain metal layers 160. The source pad 170 and the drain pad 180 aredisposed on the dielectric layer 280. As illustrated in FIGS. 1 and 2B,the source pad 170 is electrically connected to the source metal layers150, for example, through vias 175 disposed in the dielectric layer 280.As illustrated in FIGS. 1 and 2A, the drain pad 180 is electricallyconnected to the drain metal layers 160, for example, through vias 185disposed in the dielectric layer 280.

Reference is made to FIGS. 2A and 2B. In some embodiments, the activelayer 110 includes a channel layer 116 and a barrier layer 118 disposedon the channel layer 116. In some embodiments, the channel layer 116 canbe made of GaN, and the barrier layer 118 can be made of AlGaN. Theactive layer 110 further includes an insulating region 114 surroundingthe active region 112. The insulating region 114 may be formed byimplanting ions, such as oxygen, nitrogen, carbon, or the like, into theactive layer 112. In some other embodiments, the insulating region 114is a shallow trench isolation (STI). The active layer 110 may beselectively disposed on a substrate 105. The substrate 105 may be asilicon substrate or a sapphire substrate, but the claimed scope of thepresent invention is not limited in this respect. In one embodiment, thesemiconductor device 100 may further include a buffer layer (not shown)disposed between the active layer 110 and the substrate 105.

FIG. 3 is a top view of the source electrodes 120, the drain electrodes130, the gate electrodes 140, and the active layer 110 of thesemiconductor device 100 of FIG. 1. Reference is made to FIGS. 2A, 2B,and 3. In the present embodiment, the source electrodes 120 includebottom source electrode portions 122 and top source electrode portions124, and the drain electrodes 130 include bottom drain electrodeportions 132 and top drain electrode portions 134. In some otherembodiments, the top source electrode portion 124 and the top drainelectrode portion 134 can be omitted. The semiconductor device 100further includes p-type layers 145, dielectric layers 255 and 260. Forclarity, the dielectric layers 255 and 260 are illustrated in FIGS. 2Aand 2B. The p-type layers 145 are disposed between the gate electrodes140 and the active layer 110. Therefore, the semiconductor device 100 isan enhancement mode transistor. In some other embodiments, however, thesemiconductor device 100 can be a depletion mode transistor, and thepresent disclosure is not limited in this respect.

The dielectric layer 255 is disposed on the active layer 110 and has aplurality of openings 256, 257, and 258. The bottom source electrodeportions 122 are disposed in the openings 256, the bottom drainelectrode portions 132 are disposed in the openings 257, and the p-typelayers 145 are disposed in the openings 258. The dielectric layer 260 isdisposed on the dielectric layer 255 and covers the bottom sourceelectrode portions 122, the bottom drain electrode portions 132, and thegate electrodes 140. In other words, the bottom source electrodeportions 122, the bottom drain electrode portions 132, and the gateelectrodes 140 are disposed between the dielectric layer 260 and theactive layer 110. The top source electrode portions 124 are disposed onthe dielectric layer 260 and cover the bottom source electrode portions122 and the gate electrodes 140, and the top drain electrode portions134 are disposed on the dielectric layer 260 and cover the bottom drainelectrode portions 132. The top source electrode portions 124 and thetop drain electrode portions 134 extend along the first direction D1 andalternately arranged along the second direction D2.

Reference is made to FIGS. 1, 2A, and 2B. The semiconductor device 100further includes a dielectric layer 270. For clarity, the dielectriclayer 270 is illustrated in FIGS. 2A and 2B. The dielectric layer 270covers the top source electrode portions 124 and the top drain electrodeportions 134. In other words, the top source electrode portions 124 andthe top drain electrode portions 134 are disposed between the dielectriclayers 260 and 270, and the source metal layers 150 and the drain metallayers 160 are disposed between the dielectric layers 270 and 280. Thesource metal layers 150 are disposed on the dielectric layer 270 and areelectrically connected to the top source electrode portions 124, forexample, through vias 155 disposed in the dielectric layer 270. Thedrain metal layers 160 are disposed on the dielectric layer 270 and areelectrically connected to the top drain electrode portions 134, forexample, through vias 165 disposed in the dielectric layer 270. Thesource metal layers 150 and the drain metal layers 160 extend along thesecond direction D2 and alternately arranged along the first directionD1. That is, the source metal layers 150 and the top source electrodeportions 124 extend along different directions, and the drain metallayers 160 and the top drain electrode portions 134 extend alongdifferent directions. The source metal layers 150 are spaced from eachother, and the drain metal layers 160 are spaced from each other.

The top source electrode portions 124 are electrically connected to thebottom source electrode portions 122, for example, through vias 126disposed in the dielectric layer 260 and are electrically isolated fromthe gate electrodes 140. The top drain electrode portions 134 areelectrically connected to the bottom drain electrode portions 132, forexample, through vias 136 disposed in the dielectric layer 260. The topsource electrode portions 124 are spaced from each other, and the topdrain electrode portions 134 are spaced from each other.

Reference is made to FIG. 1. An orthogonal projection of the source pad170 on the active layer 110 forms a source pad region 170R, and anorthogonal projection of the drain pad 180 on the active layer 110 formsa drain pad region 180R. An orthogonal projection of the source metallayer 150 on the active layer 110 forms a source metal layer region150R, and an orthogonal projection of the drain metal layer 160 on theactive layer 110 forms a drain metal layer region 160R. A total area ofthe overlapping region OV1 between the source pad region 170R and thedrain metal layer region 160R is smaller than or equal to 40% of an areaof the drain metal layer region 160R. A total area of the overlappingregion OV2 between the drain pad region 180R and the source metal layerregion 150R is smaller than or equal to 40% of an area of the sourcemetal layer region 150R.

In the present embodiments, the source metal layer 150 and the drainmetal layer 160 extending along the second direction D2 can distributethe electric current flows from the drain electrodes 130 and the sourceelectrode 120 that extend along the first direction D1. The source pad170 and the drain pad 180 can respectively collect the current form thesource metal layer 150 and the drain metal layer 160. Therefore, thecurrent uniformity can be improved.

FIG. 4 is a top view of another semiconductor device 100 a according tosome embodiments of the present disclosure, FIG. 5A is a cross-sectionalview along line 5A-5A of FIG. 4, and FIG. 5B is a cross-sectional viewalong line 5B-5B of FIG. 4. Reference is made to FIGS. 4, 5A, and 5B.The difference between the semiconductor device 100 a and thesemiconductor device 100 of FIG. 1 is the configuration of the sourcepads 170 and the drain pads 180. In FIG. 4, the source pad 170 includesa body portion 172 and a plurality of first branch portion 174. Thedrain pad 180 includes a body portion 182 and a plurality of firstbranch portions 184. The body portion 172 of the source pad 170 extendsalong the first direction D1, and the first branch portions 174 of thesource pad 170 extend along the second direction D2. The body portion182 of the drain pad 180 extends along the first direction D1, and thefirst branch portions 184 of the drain pad 180 extend along the seconddirection D2. The first branch portions 174 of the source pads 170 andthe first branch portions 184 of the drain pads 180 are alternatelyarranged along the first direction D1. Other relevant structural detailsof the semiconductor device of FIG. 4 are similar to the semiconductordevice of FIG. 1, and, therefore, a description in this regard will notbe repeated hereinafter.

The first branch portions 174 of the source pad 170 are parallel withthe source metal layers 150, and first branch portions 174 of the sourcepad 170 are electrically connected with source metal layers 150 throughvias 175. Therefore, the total thickness of metal layers (e.g., sourcemetal layers 150 and source pad 170) that electrically connected to thesource electrodes 120 is increased. With such configuration, theresistance of source along the second direction D2 can be reduced, andthe current uniformity can be improved. Similarly, the first branchportions 184 of the drain pad 180 are parallel with the drain metallayers 160, and first branch portions 184 of the drain pad 180 areelectrically connected with drain metal layers 160 through vias 185.Therefore, the total thickness of metal layers (e.g., drain metal layers160 and drain pad 180) that are electrically connected to the drainelectrodes 130 is increased. With such configuration, the resistance ofdrain along the second direction D2 can be reduced, and the currentuniformity can be improved.

Furthermore, as illustrated in FIG. 4, an orthogonal projection of thefirst branch portions 174 of the source pad 170 are only overlapped withan orthogonal projection of the source metal layers 150, but are notoverlapped with an orthogonal projection of the drain metal layers 160.Similarly, an orthogonal projection of the first branch portions 184 ofthe drain pad 180 are only overlapped with an orthogonal projection ofthe drain metal layers 160, but are not overlapped with an orthogonalprojection of the source metal layers 150. With such configuration, thecapacitance between the first branch portions 174 of the source pad 170and the source metal layer 150 won't be increased, and the capacitancebetween the first branch portions 184 of the drain pad 180 and the drainmetal layer 160 won't be increased.

FIG. 6 is a top view of another semiconductor device 100 b according tosome embodiments of the present disclosure, FIG. 7A is a cross-sectionalview along line 7A-7A of FIG. 6, and FIG. 7B is a cross-sectional viewalong line 7B-7B of FIG. 6. Reference is made to FIGS. 6, 7A, and 7B.The difference between the semiconductor device 100 b and thesemiconductor device 100 of FIG. 1 is the configuration of the sourcemetal layers 150 and the drain metal layers 160. In FIG. 6, the sourcemetal layers 150 include first branch portion 152 and second branchportions 154. The drain metal layers 160 include first branch portions162 and second branch portions 164. The first branch portion 152 of thesource metal layers 150 extend along the second direction D2, and thesecond branch portions 154 of the source metal layers 150 extend alongthe first direction D1. The first branch portions 162 of the drain metallayers 160 extend along the second direction D2, and the second branchportions 164 of the drain metal layers 160 extend along the firstdirection D1. The second branch portions 154 of the source metal layers150 and the second branch portions 164 of the drain metal layers 160 arealternately arranged along the second direction D2. Other relevantstructural details of the semiconductor device of FIG. 6 are similar tothe semiconductor device 100 of FIG. 1, and, therefore, a description inthis regard will not be repeated hereinafter.

The length of the first branch portions 152 of the source metal layers150 is related to the resistance of the source. In some embodiments, theresistance of the source is increased when the lengths of the firstbranch portions 152 of the source metal layers 150 are increased. Assuch, the second branch portions 154 of the source metal layers 150 canreduce the resistance of the source along the first direction D1, andthe current uniformity can be improved. Similarly, the length of thefirst branch portions 162 of the drain metal layers 160 is related tothe resistance of the source. In some embodiments, the resistance of thesource is increased when the lengths of the first branch portions 162 ofthe drain metal layers 160 are increased. As such, the second branchportions 164 of the drain metal layers 160 can reduce the resistance ofthe drain along the first direction D1, and the current uniformity canbe improved.

FIG. 8 is a top view of another semiconductor device 100 c according tosome embodiments of the present disclosure, FIG. 9A is a cross-sectionalview along line 9A-9A of FIG. 8 and FIG. 9B is a cross-sectional viewalong line 9B-9B of FIG. 8. Reference is made to FIGS. 8, 9A, and 9B.The difference between the semiconductor device 100 c of FIG. 8 and thesemiconductor device 100 b of FIG. 6 is the configuration of the sourcepad 170 and the drain pad 180. In FIG. 8, the configuration of thesource pad 170 and the drain pad 180 are the same as the semiconductordevices of FIG. 4. Other relevant structural details of thesemiconductor device of FIG. 8 are similar to the semiconductor device100 b of FIG. 6, and, therefore, a description in this regard will notbe repeated hereinafter. With such configuration, the resistance alongthe first direction D1 and the second direction D2 can both be reduced,and the current uniformity can be improved.

FIG. 10 is a top view of another semiconductor device 100 d according tosome embodiments of the present disclosure, FIG. 11A is across-sectional view along line 11-11A of FIG. 10 and FIG. 11B is across-sectional view along line 11B-11B of FIG. 10. Reference is made toFIGS. 10, 11A, and 11B. The difference between the semiconductor device100 d of FIG. 10 and the semiconductor device 100 c of FIG. 8 is theconfiguration of the source pad 170 and the drain pad 180. In FIG. 10,the source pad 170 further includes a plurality of second branch portion176. The drain pad 180 further includes a plurality of second branchportion 186. The second branch portion 176 of the source pad 170 and thesecond branch portion 186 of the drain pad 180 extend along the firstdirection D1 and are alternately arranged along the second direction D2.Other relevant structural details of the semiconductor device 100 d ofFIG. 10 are similar to the semiconductor device 100 c of FIG. 8, and,therefore, a description in this regard will not be repeatedhereinafter.

The second branch portion 176 of the source pad 170 are parallel withthe second branch portion 154 of the source metal layers 150, and secondbranch portion 176 of the source pad 170 are electrically connected withsecond branch portion 154 of source metal layers 150 through vias 175.Therefore, the total thickness of metal layers that electricallyconnected to the source electrodes 120 is increased. With suchconfiguration, the resistance of source along the first direction D1 canbe reduced, and the current uniformity can be improved. Similarly, thesecond branch portion 186 of the drain pad 180 are parallel with thesecond branch portion 164 of the drain metal layers 160, and secondbranch portion 186 of the drain pad 180 are electrically connected withthe second branch portion 164 of the drain metal layers 160 through vias185. Therefore, the total thickness of metal layers that areelectrically connected to the drain electrodes 130 is increased. Withsuch configuration, the resistance of drain along the first direction D1can be reduced, and the current uniformity can be improved.

Furthermore, as illustrated in FIG. 10, an orthogonal projection of thesecond branch portions 176 of the source pad 170 are only overlappedwith an orthogonal projection of the second branch portions 154 of thesource metal layers 150, but are not overlapped with an orthogonalprojection of the drain metal layers 160. Similarly, an orthogonalprojection of the second branch portions 186 of the drain pad 180 areonly overlapped with an orthogonal projection of the second branchportions 164 of the drain metal layers 160, but are not overlapped withan orthogonal projection of the source metal layers 150. With suchconfiguration, the capacitance won't be increased.

FIG. 12 is a top view of another semiconductor device 200 according tosome embodiments of the present disclosure. The semiconductor device 200includes an active layer 210, a first active region 212A, a secondactive region 212B, first source electrodes 220A, second sourceelectrodes 220B, first drain electrodes 230A, second drain electrodes230B, first gate electrodes 240A, and second gate electrodes 240B. Thefirst source electrodes 220A, the first drain electrodes 230A, and thefirst gate electrodes 240A are disposed in the first active region 212A.The second source electrodes 220B, the second drain electrodes 230B, andthe second gate electrodes 240B are disposed in the second active region212B. The active layer 210 further includes an insulating region 214surrounding the first active region 212A and the second active region212B. In some embodiments, the insulating region 214 is a shallow trenchisolation (STI). The semiconductor device 200 further includes a gatebus 250 electrically connected with the first gate electrodes 240A andthe second gate electrodes 240B. The gate bus 250, the first gateelectrode 240A, and the second gate electrode 240B may be integrallyformed as a gate electrode. In some other embodiments, the gate bus 250may be gate metal, another metal layer, or combinations thereof. Withsuch configuration, the semiconductor device 200 can form a parallelcircuit.

In the present embodiment, the first source electrodes 220A and thesecond source electrodes 220B can be electrically connected to sourcemetal layers and source pad as illustrated in FIGS. 1, 4, 6, 8, and 10.Similarly, the first drain electrode 230A and the second drainelectrodes 230B can be electrically connected to drain metal layer andthe drain pad as illustrated in FIGS. 1, 4, 6, 8, and 10, but thepresent embodiment is not limited in this regard. For example, in thepresent embodiment, a source metal layer or a drain metal layer may bedisposed on and across a plurality of active regions. A source pad or adrain pad may be disposed on and across those active regions and areelectrically connected to the source metal layer and the drain metallayer, respectively.

In some other embodiment, the number of active regions that areconnected through the gate bus 250 can be more than two. Therefore,during the manufacturing process, a plurality of active regionsincluding source electrodes, drain electrodes, and gate electrodes canbe formed first. The electric connection between those gate electrodesin different active regions through gate bus can then be determineddepend on the application requirement.

FIG. 13 is a top view of another semiconductor device 200 a according tosome embodiments of the present disclosure. The first gate electrodes240A include bottom electrode portions 242A and top electrode portions244A. The second gate electrodes 240B include bottom electrode portions242B and top electrode portions 244B. The top electrode portions 244A,244B are electrically connected to the bottom electrode portions 242A,242B through vias 246A, 246B, respectively. The top electrode portions244A of the first gate electrodes 240A and the top electrode portions244B of the second gate electrodes 240B are electrically connectedthrough a gate bus 250 a. That is, the gate bus 250 a is laterallyextends from the top electrode portions 244A of the first gateelectrodes 240A and the top electrode portions 244B of the second gateelectrodes 240B.

Similarly, the first source electrodes 220A include bottom electrodeportions 222A and top electrode portions 224A. The second sourceelectrodes 220B include bottom electrode portions 222B and top electrodeportions 224B. The top electrode portions 224A, 224B are electricallyconnected to the bottom electrode portions 222A, 222B through vias 226A,226B, respectively. The first drain electrodes 230A include bottomelectrode portions 232A and top electrode portions 234A. The seconddrain electrodes 230B include bottom electrode portions 232A and topelectrode portions 234B. The top electrode portions 234A, 234B areelectrically connected to the bottom electrode portions 232A, 232Bthrough vias 236A, 236B, respectively.

In the present embodiment, the top electrode portions 224A of the firstsource electrodes 220A and the top electrode portions 224B of secondsource electrodes 220B can be electrically connected to source metallayers and source pad as illustrated in FIGS. 1, 4, 6, 8, and 10.Similarly, the top electrode portions 234A of first drain electrode 230Aand the top electrode portions 234B of second drain electrodes 230B canbe electrically connected to drain metal layer and the drain pad asillustrated in FIGS. 1, 4, 6, 8, and 10, but the present embodiment isnot limited in this regard.

FIG. 14 is a top view of another semiconductor device 300 according tosome embodiments of the present disclosure. FIG. 15 is a circuit diagramof the semiconductor device in FIG. 14. Reference is made to FIG. 14 andFIG. 15. The semiconductor device 300 includes an active layer 310, afirst active region 312A, a second active region 312B, first sourceelectrodes 320A, second source electrode 320B, first drain electrodes330A, second drain electrode 330B, first source metal layers 350A,second source metal layers 350B, first drain metal layers 360A, seconddrain metal layers 360B, a source pad 370, and a drain pad 380. Thefirst source electrodes 320A, the first drain electrodes 330A, the firstsource metal layers 350A, and the first drain metal layer 360A aredisposed in the first active region 310A. The second source electrodes320B, the second drain electrodes 330B, the second source metal layers350B, and the second drain metal layer 360B are disposed in the secondactive region 310B. The active layer 310 further includes an insulatingregion 314 surrounding the first active region 312A and the secondactive region 312B. In some embodiments, the insulating region 314 is ashallow trench isolation (STI).

In the present embodiment, the first source metal layers 350A areelectrically connected to the first source electrodes 320A, and thesecond source metal layers 350B are electrically connected to the secondsource electrodes 320B. The first drain metal layers 360A areelectrically connected to the first drain electrodes 330A, and thesecond drain metal layers 360B are electrically connected to the seconddrain electrodes 330B and the first source metal layers 350A.

As illustrated in FIG. 15, a terminal s1 indicates the current flowsfrom the first source electrodes 320A to the first source metal layers350A, a terminal s2 indicates the current flows from the second sourceelectrodes 320B to the second source metal layers 350B and the sourcepad 370, a terminal d1 indicates the current flows from the first drainelectrodes 330A to the first drain metal layers 360A and the drain pad380, and a terminal d2 indicates the current flows from the second drainelectrodes 330B to the second drain metal layer 360B. The terminal s1 iselectrically connected with the terminal d2. With such configuration,the semiconductor device 200 can form a series circuit.

Reference is made to FIG. 3, FIG. 14, and FIG. 15. In some embodiments,the semiconductor device 300 further includes first gate electrodes andsecond gate electrodes similarly to the gate electrodes 140 asillustrated in FIG. 3, but the present disclosure is not limited in thisregard. A terminal G1 indicated the first gate electrodes disposed onthe first active region 312A, and a terminal G2 indicated the secondgate electrode disposed on the second active region 312B.

In some embodiments, the first source metal layers 350A and the secondsource metal layers 350B may include first portion and a plurality ofsecond portions similarly to the embodiments illustrated in FIGS. 6, 8,and 10. In some embodiments, the first drain metal layers 360A and thesecond drain metal layers 360B may include first portion and a pluralityof second portions similarly to the embodiments illustrated in FIGS. 6,8, and 10. Furthermore, the source pad 370 and the drain pad 380 mayinclude body portion and a plurality of first branch portions or secondbranch portions similarly to the embodiments illustrated in FIGS. 4, 8,and 10.

In some other embodiment, the number of active regions that areconnected through the gate bus 250 a can be more than two. Therefore,during the manufacturing process, a plurality of active regionsincluding source electrodes, drain electrodes, and gate electrodes canbe formed first. The electric connection between those source electrodesand the drain electrodes in different active regions can then bedetermined depend on the application requirement.

Although the present invention has been described in considerable detailwith reference to certain embodiments thereof, other embodiments arepossible.

Therefore, the spirit and scope of the appended claims should not belimited to the description of the embodiments contained herein.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentinvention without departing from the scope or spirit of the invention.In view of the foregoing, it is intended that the present inventioncovers modifications and variations of this invention provided they fallwithin the scope of the following claims.

What is claimed is:
 1. A semiconductor device, comprising: an activelayer having an active region; a source electrode, a drain electrode,and a gate electrode disposed on the active region of the active layerand extending along a first direction; a source metal layer disposed onthe active region and electrically connected to the source electrode; adrain metal layer disposed on the active region and electricallyconnected to the drain electrode, wherein the drain metal layercomprises a first branch portion extending along a second directiondifferent from the first direction, and an orthogonal projection of thedrain metal layer on the active layer forms a drain metal layer region;and a source pad disposed on the active region, wherein the source padis electrically connected to the source metal layer, wherein the sourcepad comprises a body portion, the body portion has a longestcontinuously straight section extending along the second direction toform an equal width, and the equal width extends along the firstdirection to form the longest continuously straight section, and anorthogonal projection of the source pad on the active layer forms asource pad region that overlaps the drain metal layer region, and anarea of an overlapping region between the source pad region and thedrain metal layer region is smaller than or equal to 40% of an area ofthe drain metal layer region, and the entire overlapping region islocated within an orthogonal projection of the body portion of thesource pad on the active layer.
 2. The semiconductor device of claim 1,wherein an orthogonal projection of the source metal layer on the activelayer forms a source metal layer region, and the semiconductor devicefurther comprises: a drain pad disposed on the active region, whereinthe drain pad is electrically connected to the drain metal layer, anorthogonal projection of the drain pad on the active layer forms a drainpad region that overlaps the source metal layer region, and an area ofan overlapping region between the drain pad region and the source metallayer region is smaller than or equal to 40% of an area of the sourcemetal layer region.
 3. The semiconductor device of claim 1, wherein thesource electrode comprises a bottom electrode portion and a topelectrode portion, wherein the bottom electrode portion of the sourceelectrode is disposed between the top electrode portion of the sourceelectrode and the active layer.
 4. The semiconductor device of claim 1,wherein the drain electrode comprises a bottom electrode portion and atop electrode portion, wherein the bottom electrode portion of the drainelectrode is disposed between the top electrode portion of the drainelectrode and the active layer.
 5. The semiconductor device of claim 1,wherein the source metal layer further comprises a second branch portionextending along the first direction.
 6. The semiconductor device ofclaim 1, wherein the source pad comprises: a first branch portionextending along the second direction different from the first direction.7. The semiconductor device of claim 6, wherein the source metal layercomprises a first branch portion extending along the second directionand a second branch portion extending along the first direction.
 8. Thesemiconductor device of claim 7, wherein the source pad furthercomprises a second branch portion extending along the first directionand electrically connected to the second branch portion of the sourcemetal layer.
 9. The semiconductor device of claim 1, wherein the drainmetal layer further comprises a second branch portion extending alongthe first direction.
 10. The semiconductor device of claim 1, whereinthe drain pad comprises: a body portion extending along the firstdirection; and a first branch portion extending along the seconddirection different from the first direction.
 11. The semiconductordevice of claim 10, wherein the drain metal layer comprises a secondbranch portion extending along the first direction.
 12. Thesemiconductor device of claim 11, wherein the drain pad furthercomprises a second branch portion extending along the first directionand electrically connected to the second branch portion of the drainmetal layer.
 13. The semiconductor device of claim 1, wherein the firstdirection is substantially perpendicular to the second direction.